The formation of wellbores for the purpose of exploration or extraction of natural resources such as oil, gas, and water is a valuable yet time consuming and expensive field. Completion of wellbores includes the process of making a well ready for production or injection. Some types of completion systems include a tubular which supports subs enabling a frac pack operation, isolation packing, and gravel pack operations, and production sleeves having screens for bringing production fluid from downhole to surface. Once wells are completed using this type of completion system, production tubing and associated downhole tools can be run into the wellbore.
Advances in completion technology have led to the emergence of multi-zone systems where zones within the formation are separated, such as by packers and sand control configurations and operations, and each zone can be separately treated, fractured, or produced from, which saves time and inevitably reduces expenses. A multi-zone single trip (“MST”) completion system reduces time and expenses even further by completing multiple zones in one trip.
A multi-zone single trip (“MST”) completion system is shown in FIGS. 1A and 1B. The MST system includes a number of subs attachable together to form a completion string 10. It should be understood that only a portion of the completion string 10 is shown, as the completion string 10 can include as many subs, tubing joints, and sleeves necessary for spanning as many zones as desired. As shown in FIG. 1A, the completion string 10 includes, in part, an automatic locating assembly or “autolocator” 12 to locate the completion string 10 in its various conditions such as, but not limited to pickup, run in, and set down positions. Inverted seals, which can include uphole and downhole inverted seals 14, 16, are provided within an inner diameter of the completion string 10 and are usable in a fracing operation. An isolation packer 18 is included in the completion string 10 and may include slips for engaging a casing or wellbore. The isolation packer 18 is located between the uphole inverted seals 14 and a frac sleeve 20. The frac sleeve 20 of the completion string 10 is located between the isolation packer 18 and downhole inverted seals 16.
The completion string 10 for multi-zone applications further includes multiple sets of the illustrated features which are spaced out with screen joints and production sleeves in between for production purposes, as shown in FIG. 1B. As shown in FIG. 1B, and downhole of the frac sleeve 20 and inverted seals 16, the MST system further includes shear out safety joint 24, production valves, also known as production sleeves 26 having a selective profile, that are capable of opening and closing depending on whether or not a particular zone should be opened for production, and a screen 28 extending along the length of the production zone. In one exemplary embodiment, a standard well is completed using a service string consisting of, but not limited to, a frac port, opening tool, and closing tool (not shown). Upon completion of the final zone, the service string may be removed from within the completion string 10. Upon removal, the closing tool on the service string closes all sleeves as it traverses through the completion string 10 in the uphole direction. Removal of the service tool leaves a bore 22 in the completion string 10 for receiving the production string. Production tubulars are then run into the wellbore and are connected to the completion string 10 enabling a continuous bore to surface. A separate opening/closing tool (not shown) can then be run in the completion string 10 for selectively opening and closing the production sleeves 26 to initiate production through the production string, where such determination may be made by an operator or by a sensing device, however this requires additional time since the opening/closing tool then needs to be removed from the completion string 10. Thus, production is initiated by selectively opening and/or closing selected production sleeves 26 using a work string such as by wireline, coiled or standard tubing. When multiple zones are accessed with the completion system 10, subsequent opening and/or closing of other selected production sleeves 26 requires additional runs of the work string.